Provided are diamondoid salts, electrolytes comprising the diamondoid salts, and electrochemical devices incorporating the diamondoid salts or electrolytes. In embodiments, an electrolyte for an electrochemical device comprises a metallic salt and a diamondoid salt, the diamondoid salt comprising a diamondoid-functionalized cationic core and a counter anion, the diamondoid-functionalized cationic core comprising a cationic core and a diamondoid group covalently bound to the cationic core.